Remote control system



Dec. 17, 1929. TAYLOR 1,739,531

REMOTE CONTROL SYSTEM Filed May 12. 1926 INVENTOR AT] ORNEY Patented Dec. 17, 1929 UNITED STATES PATENT, OFFICE EDMUND R. TATLOB, OI NEW YORK, N. Y., ASSIGNOB TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK REMOTE CONTROL SYBTEH Application fled Kay 12, 1988. Serial No. 108,653.

,This invention relates to volume control systems and particularly to arrangements in signaling systems for simultaneously controlling at a sending station the volume of transmission at a plurality of receiving stations of such systems.

The range of volume change occurring at the source of a program of news, music or the like is in many cases much greater than can conveniently be transmitted in a transmission system such as a radio broadcasting or public address system. The reasons for the limitation in the range of these systems are that if the transmitted energy rises to a great height, the system will be overloaded, causing the quality to be distorted; on the other hand, if the energy sinks to a low level it is drowned by interfering noises which are inherent to such systems. Accordingly, it is customary to regulate the gain of the amplifier at the sending station of such a system so that the transmitted energy is ke t within the proper limits. This regulation ecomes apparent at the receiving station in several ways, the most serious of which are perhaps as follows: (a) There is a sense of restrictedness or constraint as though the artist at the sending station was trying to swing into a full volume range but was continuously prevented from doing so; (b) the program is jerky and uneven because the average operator who controls the gain of the system cannot anticipate the extremes of the volume ran e and hence cannot smoothly control the v0 ume between these extremes; (a) there is an inherent signal distortion due to the fact that the volumeamplification characteristic of the system is not maintained constant.

These difiiculties, and numerous others of a lesser nature, can be alleviated to a large degree if the amplifier at the receiving end of the system is operated in such a manner that the over-all gain of the system is approximately constant at all times, i. e., the gain changes. of the amplifier at a receiving station are equal to the gain changes of the amplifier at the sending station, and these changes are in opposite directions. Such a system can be brought about by arrangements which produce simultaneous and com lementar changes in the gain of the amp ifier at eacii receivin station when the gain of the amplifier at tie sending station is changed.

In this invention'there will be described the arrangements for accomplishing these ends, which employ comparatively inexpensive apparatus. It is to be understood, however, that in the articular embodiment of the invention to e described, in which the gain changes at each of a plurality of receiving stations are equal to the gain changes at the sending station, sli ht modifications well known to those skille in the art may be made so that a change in the gain of the amplifier at the sending station will bear any fixed and predetermined relation to the change in the gain taking place at each of the receiving stations.

It may be said that it is one of the objects of this invention to provide a plurality of relays at each receiving station of a transmission system, one relay being associated with each of the steps of the volume adjusting means at each receiving tation, so that as76 the volume at the sending station is changed, the relays at the receiving stations will be successively operated to brmg about simultaneous and complementary changes in the volume. 4 g

It is a further object of this invention to provide a plurality of indicating devices, one indicating device associated with each ste at each receivin station, so that there wil he means for in icating the gain of the amplifier at each receiving station.

VVhile the nature of the invention will be pointed out with particularity in the apded claims, the invention itself, both as to 1ts further objects and features, will be better understoodv from -the detailed description hereinafter following when read in connection with the accompanying drawing showone embodiment of the invention. 11 the articular embodiment of the invention w ich is given merely for the purpose of illustration, there is one transmitting station I and there are two receiving stations 1 and I the apparatus at the receiving station I being identical with the apparatus 100 sending station. Thus, therewill be provided arm means for establishin a make or a break whenever it is desire to change the gain of the amplifier at each receiving station by one step. Alternating current and pulses of direct current are transmitted over the main line ML- when it is desired to increase the gain of the amplifier at the sending station,

-whereas pulses of direct current are transmitted when it is desired to decrease the gain of the amplifier at the sending-station. At each receiving station a plurality ofrelays S to S inclusive, are so arranged that each is associated with one of the resistances R to R inclusive, of the potentiometer at each receiving station, these relays being successively responsive in one direction to pulses of. direct current and beingsimilarly responsive in the opposite direction to alternatingcurrent and pulses of direct current. As stated above, it is one of the features of this invention to provide a plurality ofindicating lam s L to L inclusive, to indicate the gain of t e amplifier at each receiving station. 7

Two potentiometers are provided at the sending station, one of these in addition to the usual and well known gain control potentiometer. The resistances r to r. inclusive, are connected across the source of supply P. The first potentiometer, has an one end of which moves over taps 0 to 6, inclusive, to connect any number of the resistances r, to r inclusive, to the amplifier A at the sending station. The other end of the arm A moves over the conductor E. Thus the arm A is moved clockwise or counterclockwise as the gain of the amplifier at the sending station is to be increased or decreased, respectively. The other potentiometer has an arm B mounted on a shaft D which is common also to the arm A of the first potentiometer. The arms A and B are so arranged.

as to rotate together and to make corresponding contacts atthe same time, but they are insulated electrically from each other. One end of the arm B moves over taps 0' to 6',

inclusive, the taps 1, 3' and 5' being con- .nected to ground through a choke coil F, the

the amplifier at the sending station, but is insulated from the arm B when the rotation is counterclockwise to decrease the ain of the amplifier at the sending station. ne end of the arm C moves over a conductr E", which is connected through a condenser K to a sourceof alternating current G Accordingly, when the arm C is rotated clockwise to increase-the gain of the amplifier at the sendin tation, alternating current and pulses of ct current are transmitted over the main "line ML. The alternating current circuit between stations I and I, inclues the alternating current nerator G, the condenser K the conductor the arm C, the arm B, the conductor E, the secondary winding of the transformer T -,-the main line 1 ML, the primary windingof the transformer T a condenser K and a relay S The direct current circuit between these stations includes-the choke coil F, the arm B, the conductor E, the secondary winding of the transformer T the .'main line ML, the primarywindingof thet'ransformer T a relay S, and a battery B The choke coil F pre vents the alternating current of the enerator G from being short-circuited throng the tentiometer, and similarly the condenser 1 prevents the arm C from being connected to groundthrough the generator G. I

As shown in the figure arm A rests-ontap 6 connectin resistances A to n, inclusive, to the input 0 the amplifier A at the sending station I for the condition of'maximum gain at that station. Arm B rests on tap 6, and therefore the direct current circuit heretofore described is open. None of relays at the receiving station 1 are operated, and hence the input of the am lifier A is connected across the resistance 0 through the armature 1 of the relay S When the arm B moves from tap 6' to tap 5' and makes electrical contact with tap 5', the

relay S, becomes energized so that current flows from a battery B,.through the winding J of relay S conductor 12, indicating lamp L the winding of the relay 8;, the'armature 2 o the relay S and ground. The armature 3 of the relay S becomes attracted to connect ground to the winding of the relay S before the armature 2 of the relay S opens its contact When the armature '1 of the relay S closes its contact resistances R and R are connected to the input of the amplifier A and shortly afterwards the armature 1 of the relay S opens, disconnecting the circuit which formerly connected theinput of the amplifier A with the resistance B and hence the gain of the amplifier A, is increased without its input being open-circuited. When the arm B moves counterclockwise from tap 5 to tap 4' and makes electrical contact with the tap 4', the-relay S becomes deenergized so that current now' flows from the battery B5 through the winding of the relay S conductor 11, theindicating lamp L, the windin of the relay S the armature 2 of the re ay S conductor 14 and ground. The armature 3 of the relay S connects ground to the winding of said relay before the relay S, becomes deenergized. When the armature 1 of the relay S closes its contact, resistances R to R inclusive, are connected to the input of the amplifier A As the arm B moves counterclockwise from tap 4 to tap 3 and makes electrical contact with ta 3, the relay 8, becomes energized by the how of current from the battery B therethrough. Current now flows from battery B, through the winding of the relay S conductor 12, the indicating lamp L the winding of the relay 3,, the armature 2 of the relay S conductor 13 and. ground. The armature 3 of the relay S connects ground to the winding thereof before the relay S becomes deenergized. When the armature 1 of the relay S closes its contact, resistances R to R inclusive, are connected to the input of the amplifier A W hen the arm B moving counterclockwise makes contact with the tap 2, the relay S becomes deenergized so that current now flows from the battery B through the winding of the relay S conductor 11, the indicating lamp L.,, the winding of the relay S the armature 2 of the relay S conductor 14 and ground. The annature 3 of the relay S connects ground to the winding thereof before the relay S becomes deenergized.

As the arm B moves counterclockwise and makes electrical contact with the tap 1, the relay S becomes energized so that current flows from the battery B through the winding of the relay S conductor 12, the indicating lamp L the winding of the relay S5, the armature 2 of the relay S conductor 13 and ground. The armature 3 of the relay S puts ground on the winding of said relay, before the relay S becomes deenergized. When the armature 1 closes its contact, re-

' sistances R to R inclusive, are connected to the input of the amplifier A Finally, as the arm B moves counterclockwise away from tap 1, the relay S becomes deenergized, so that current flows from the battery B through the winding S conductor 11, the indicating lamp L the winding of the relay S the armature 2 of the relay S conductor 14 and ground. The armature 2 puts ground on the winding-of the relay S before the relay S becomes deenergized; The armature 1 of the relay S by closing its contact, brings about a short-circuit for the input of the amplifier "A so that'no signals may be transmitted through the amplifier A To increase the gain of the amplifier A at the sending station 1,, the arm C drives the gized, and remain energized as long "as it is desired to increase thegain of the amplifier A, at the sending station L. Consequently, the relay S becomes energized by the flow of current through the winding of said relay the battery B No change is yet effected in the system. As the arm C drives the arm B clockwise to the point where the an; makes electrical contact with the tap 1, the relay f5 becomes energized and the relays S and 3,, remain energized. Moreover, the relays S and S momentarily remain energized on account of the make-before-break contacts of relay S so that current now flows from the battery B through the winding of the relay S the conductor 12, the indicating lamp L and the winding of the relay S the armature 3 of the relay S ,.conductor 16 and ground. The armature 3 of the relay S puts ground on the winding of said relay before the relay S becomes deenergized. \Vhen the armature '1 of the relay S closes its contact, resistances R to R inclusive, are connected to the input of the amplifier A As the arm C moves the arm B clockwise to the point where it makes electrical contact with the tap 2, the relay S becomes deenergized, whereas relays S and 8,, remain energized. Current now flows from battery B through the winding of the relay S conductor 11, the indicating lamp L,,, the winding of the relay S the armature 4 of the relay S conductor 17 and ground. Armature 3 of relay S puts ground on the winding of said relay before the relay S becomes deenergized. Vhen the armature 1 of the relay S closes its contact, resistances R to R are connected to the input ofthe amplifier A lVhen the arm B makes elecv trical contact with the tap 3, the relay S becomes energized so that current flows from the battery B through the winding of the relay S the conductor 12, indicating lamp L the winding of the relay S armature 4 of the relay S. conductor 16 and ground. Armature 3 of the relay S locks the winding of said relay. Besistances B to B inclusive, are now connected to the input of the amplifier A \Vhen the arm B makes contact with the tap 4, the relay S becomes deenergized and current flows from the battery B through the winding of relay S conductor 11, indicating lamp L winding of the relay S5, the armature 4 of the relay S conductor 17 and ground; Armature 3 locks the winding of said relay. Resistances R to R inclusive, are now connected to the input of the amplifier A When the arm B makes contact with the tap 5', relay S becomes energized and current flows from the battery B through the winding of the relay S conductor 12, indicating lamp L, the winding of the relay S armature 4 of the relay S conductor 16 and ground. The armature 3 of the relay S locks the winding of said relay. Resistances R and R are now connected to the input of the amplifier A When arm B makes contact with the tap 6', relay S becomes deenergized, and relays S and S also become deenergized. Resistance R is then connected to the input of the amplifier A by armature 1 of the relay S It is to be specially noted that the control of the volume takes place at one station which has a control device thereat for controlling the transmission of alternating current and pulses of direct current to operate a plurality of relays located at two or more other stations, the apparatus at one of which is shown in detail. Whenever the gain of the amplifier at the sending station increases, there will be a simultaneous and complementary change in the gain of the amplifier at each of the receiving stations. Indicating devices provide means .for quickly determining the state of the volume transmitted over the main line of the system.

It is to be understood that, while in the embodiment of the invention shown herein alternating current and pulses of direct current are transmitted over the main line of the system to effect simultaneous and complementary changes in the gain of the amplifiers at the sending and receiving stations of the system, it is within the scope of this invention to provide any pair of alternating currents of different frequencies in place of the alternating current and .the' direct cur rent (which obviously has zero frequency) or to use current reversals well knownin the art for accomplishing these objects.

While the invention has been shown and described in one particular embodiment, it is to be distinctly understood that the invention is capable of embodiment in other and widely varied arrangements without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is: 1. In a transmission system, a transmitting medium interconnecting a sending station and a plurality of receiving stations, volume adjusting means at each station, a control switch at the sending station, a plurality of relays at each receiving station, means operated by a change in the setting of said switch to transmit alternating current and pulses of direct current between said stations for rendering said relays responsive to said impulses to efiect simultaneous and complementary adthe receiving stations.

2. In a transmission system, a transmitting justnients of the volume at the sending and medium interconnecting a sending station and a receiving station, volume adjusting means at each station, a control switch at the sending station, said control switch controlling the transmission of alternating current and successive pulsations of direct current as the volume at the sending station is increased and of successive pulsations of direct current as the volume at the sending station is decreased, and step-by-step means responsive to the transmission of said ulsations to simultaneously efi'ect equal an complementary step-by-step adjustments of the volume at the receiving station as are taking place at the sending station.

3. In a transmission system, a transmitting medium interconnecting a sending station and a receiving station, volume adjusting means at'each-station, a control switch at the sending station, said control switch simultaneously controlling the volume at both the sending and receiving stations, said control switch transmitting alternating current and successive pulsations of direct current as the volume at the sending station is increased,

said control switch transmitting successive pulsations of direct current as the volume 7 at the sending station is decreased, and stepby-step means responsive to the transmission of said pulsations to simultaneously efl'ect equal and complementary step-by-step adjustments of the volume at the receiving station as are taking .place at the sending station.

4. In a transmission system, a transmitting medium interconnecting a sending station and a receiving station, volume adjusting means at each station, means atthe sending station for controlling the volume at both the sending and receiving stations, means operated by said controlling means for transmitting direct current and alternating current impulses through the transmitting medium between stations, a plurality of relays at the receiving station, means for rendering said relays responsive to said impulses to effect simultaneously complementary adjustments of the volume at the sending and receiving stations, and means for indicating the state of the volume adjusting means.

and a plurality of relays at the receiving station for controlling the volume adjusting meansthereat, said relays at the receiving station being operated successively in one order in response to said alternating current and the characteristic direct current impulses transmitted over the-main line to decrease the volume, said relays at the receiving station being operated successively in reverse order in response to the other characteristic direct current impulses transmitted over the main line to increase the volume.

6. In a transmission system, a main line interconnecting a sending station and a receiving station, volume adjusting means at each station, a switch at the sending station for controlling the volume adjusting means thereat, means responsive to the manipulation of said switch in one direction to transmit alternating current of suitable frequency and characteristic direct current impulses over the main line, means responsive to the manipulation of said switch in the opposite direction, to transmit other characteristicdirect current impulses over the main line, a plurality of relays at the receiving station for controlling the volume adjusting means thereat, said relays at the receiving station being operated successively in one order in response to said alternating current and the characteristic direct current impulses transmitted over the main line, said relays at the receiving station being operated successively in the reverse order in response to the other characteristic direct current impulses transmitted over the main line, and means associated with said relays for indicatin the state of the volume adjusting means at t e receiving station.

7. In a transmission system, a main line interconnecting a sending station and a receiving station, volume adjustin means at each station, a switch at the sen ing station for controlling the volume adjusting means thereat, means responsive to the manipulation of the switch in one direction to transmit alternating current of suitable frequency as well as direct current ulsations over the main line, means responsive to the manipulation of the switch in the other direction to transmit other direct current pulsations over the main line, a lurality of relays at the receiving station or controlling the volume adjusting means thereat, means for successively operatin the relays in one order inresponse to sai alternating current of suitable frequency and saiddirect current p ulsations, and means for successively operatmg the relays in the other order in response to the other direct current pulsations.

8. In a transmission system, a main line interconnecting a sending station and a receiving station, volume ad usting means at each station, a switch at the sending statlon for controlling the volume ad usting means thereat, means responsive to the manlpulation of the switch in one direction to transmit current of one frequency over the mam line, means responsive to the manipulation of the switch in the other direction to transmit current of another frequency over themain line, a plurality of relays at the receiving statlon for controlling the volume ad usting means thereat, means for successively operating the relays in one orthe other order in response to current of one or the other frequency, and means for indicating the state of the volume indicating means. a

9. In a transmission system, a main line interconnecting a sending station and a receiving station, volume adjusting means at each station, a switch at the sending station for controlling the volume adjusting means thereat, means responsive to the manipulation of the switch in one direction to transmit pulses of direct current overthe main line, means responsive to .the manipulation of-the switch in the other direction to transmit a1- ternating current and pulses of direct current over the main line, a plurality of rela s at the receiving station for controlling t e volume adjusting means thereat, means for successively operating the relays in one order in response to the pulses of direct current, means for successively operating the relays in the other order in response to alternating current and pulses of direct current, and volume indicating means at the receiving station.

10. A system for simultaneously controlling from a central station the gain of a plurality ofamplifiers at remote stations, the amp ifiers at the various remote stations being connected to the central station by a common transmitting medium suitable for the transmission of speech, including means for transmitting characteristic alternating current impulses over said transmitting medium between the central station and all of the remote stations when the ain is to be changed, and a plurality of re ays at each remote station successively responsive to said characteristic alternating current impulses to produce the required change in the gain.

11. A system for simultaneously controllingfrom a central station the volume of transmission at a plurality of remote stations, comprising means whereby the volume changes at each remote station and the volume changes at the central station may be produccd which are equal and complementary,

said volume changes at each remote station Y Y distant stations as are takin sponsive thereto for rendering equal and complementary volume changes at each of the g place at the central station.

In testimony whereof, I have signed. my name to this specification this 11th day of May, 1926.

EDMUND R. TAYLOR. 

